Tanning agents and a process of preparting them



Patented Dec. 18, 1951 TANNING AGENTS AND A PROCESS OF PREPARING THEM Christoph Nikolaus Jakobus Thomsen, deceased, late of Taunus, Germany, by Gertrfid Thomsen, administratrix, Kelkheim-Miinster im Taunus, Germany, assignor to Farbwerke Hoechst vormals Meister Lucius & Bruning, Frankfurt (Main), Hoechst, Germany No Drawing. Application May 13, 1949, Serial No.

' 93,193. In Germany October 1, 1948 .5 Claims.

- clearer tint, but their resistance to salts and the compatibility with extracts is generally insufficient. It is necessary for the production or serviceable tanning agents to reduce their content of electrolytes, which may be carried out by washing with water or salt liquors.

It is an object of this invention to prepare new and valuable tanning agents which are free from the drawbacks connected with the known tanning agents prepared with the aid of colophony.

It has been found that condensation products having a tanning action and very good properties are obtainable by sulfonatin a mixture of 0010- phony and a naphthol, reacting the sulfonation product with a phenol alcohol if desired in the presence of a free phenol, and then reacting the resulting condensation product with-formaldehyde. Brown tanning agents are obtained which strike through rapidly and show on analysis a content of tanning matter up to 95 parts by weight per 100 parts. by weight of dry residue, and which maintain their good tanning action even at high pH values. produce a well plumped leather of an excellent rendement and great firmness, which is similar to bark-tanned leather.

For the sulfonation in admixture with 0010- phony either alpha-naphthol or beta-naphthol are suitable. The sulfonation does not involve any particular difliculties, it is carried out at raised temperatures in the manner usual for such sulfonations. In order to ensure that the sulfonation occurs satisfactorily and that, before all, a sulfa-group enters also the molecule of the colophony, it is of advantage to heat the sulfonation mixture for some time to temperatures of at least 110 C. It is of advantage to keep the temperature at the beginning of the operation somewhat lower, e. g. approximately between 70 and 100 C. The sulfonating agent may be added to the mixture of naphthol and colophony or the naphthol and/or colophony may be introduced into the sulfonating agent.

In many cases they z-l.

The introduction of colophony should be regulated so as to avoid foaming over. The usual sulfonating agents may be used, for instance sulfuric acid of to per cent strength, fuming sulfuric acid or chlorosulfonic acid. The relative proportions of colophony and naphthol may be varied within wide limits, namely from 1 part of colophony to 1.3 up to 6 parts of naphthol. The proportion of 1 part of colophony to 2 parts of naphthol is of advantage. During the reaction monosulfonic acids of the colophony and of the naphthol are formed predominantly. Naphtholdisulfonic acids are also formed to a small extent.

The next step of the process is the reaction of the naphthol-colophonysulfonic acids with a phenol alcohol. Phenol-alcohols are water soluble, low molecular reaction products from phenols with formaldehyde, expediently in the presence of water, formaldehyde-yielding substances or other compounds capable of introducing CH2OH-gr0ups into the aromatic nuclei. The operation is performed by reacting less than 1 mol of formaldehyde with 1 mol of phenol. It is of special advantage to use only about 0.4 mol of formaldehyde per one mol of phenol. The manuiacture of such phenol alcohols is generally known. It is carried out by reacting a phenol with formaldehyde in the presence of a small quantity of an alkaline condensing agent, such as sodium carbonate or sodium hydroxide solution. In order to accelerate the reaction, temperatures of up to 100 C. may be used. As an example for the reaction of another compound capable of introducing CH2OH-groups there may be mentioned the reaction of a phenol with methylene chloride in the presence of sodium hydroxide solution and, if necessary, under pressure.

-As phenols may be used for example phenol itself, cresols, furthermore mixtures of cresols or of cresols with a phenol, finally commercial products containing mixtures of mononuclear phenols, such as the so-called phenol oil containing phenol itself, cresols, xylenols and phenols with two phenolic hydroxyl groups.

The so obtained phenol alcohols, generally in an aqueous solution, are reacted with the reaction mixture containing naphthol-colophonysulfonic acids. The condensation is suitably conducted at temperatures of approximately 90-100 0., it occurs without difiiculties and is generally terminated after about /2 hour. v The reaction is finished when the reaction product readily dissolves in water. In this case, too, the proportions between sulfonic acid and phenol alcohol may be varied within relatively wide limits. However, it proved to be of advantage to apply such aproportion of phenol alcohol that about 1 part of the phenol or the phenols used for the manufacture of the phenol alcohol corre- 5 sponds to about 1 part of the originally used. naphthol.

If during the reaction of thephenolalcohol a free phenol is still present, the total amount of the free phenol and that used for the phenol.

alcohol advantageously equals approximately the quantity of the originally used naphthol. As; such phenols the foregoingphenolscan likewise. be employed.

The last step of the process comprises the after-treatment of the condensation products: with formaldehyde, which is advantageously performed after dilution of the condensation product by means of water. t takes placeat temperatures of about 90-100" C. The propornon: of formaldehyde-' may varywithin wide limits- It is recommended to use-such" a total amount of formaldehyde (i. e. of the formaldehydeusedfor the manufacture of the phenol alcohol plus the formaldehyde used forthe aftertreatment) that approximately 0.75 up 1700.95. mol of formaldehyde corresponds toapproxi-- mately l mol of the total amount of phenol ap-' plied (i. e. the phenol used for the manufacture of the phenol alcohol plus the phenol possibly present in a freestate). Instead of free formaldehyde, compounds may be used yielding form-- aldehyde under the reaction conditions, forinstance hexamethylenetetramineembodying simultaneously the advantage that the ammonia set free at the-same time neutralizes the'tanning agent.

The new tanning agents formed in the processdescribedabove are neutralized in the usual way with organic acids and adjusted to thedesired 40 acid-ity.- i'heyare applied in form of aqueous solutions (of about 50 450 per cent strength) as obtained according to'this process.

The-iollowingexamples serve to illustrate-the invention, but they are'not intended to limit it thereto,-the parts being by weight:

l. 280 parts of beta-naphtholin powderedform arerapidly added at a temperature of 70--90"C. and parts of colophony at a temperature of- 99-406 C. to 280 parts of sulfuric acid of 100-50 per cent strength, while stirring: Afterthese additions, the mixture is heated for alittletime at 115 C. and cooled'to 95 C. 460 parts of a liquid condensatioi-i product of cresol-phenol and formaldehyde are then introduced, whilestirring vigorously. The -mixture is then diluted with-80 parts of water, and is further condensed at 95 C. with 153 parts of formaldehyde solution of 30 per cent strength diluted by 39 parts of water.

The condensation product of thephenolsand formaldehyde is prepared by heating for-'3 hours: a-tatemperature of C., while stirring, am'ix ture consisting of 160' parts of phenol; IBO'partsof cresol, 140 parts of formaldehyde solution of 30 per cent strength and 0.7 part of anhydrous sodium. carbonate.

The tanning: agent is neutralized with an aqueous solution of ammonia, and adjusted with acetic acid to an acidity such that 10 grams of the mixture require 10 cc. of an n-solution of ture of colophony, and; a naphthol atelevated temperatures, reacting a. phenol alcohol with the product thus. obtained. and then causing form-.-

aldehyde to act atgtemperatures of about 590-100 1 C. upon the, condensationproductthus obtainedsaid products showing good: tanning: properties.

even at highgpH values..

2. The products obtained: by sulfonating. a

mixture of colophony-and beta-naphtholat elevated; temperatures, reaoting.. a:-. phenol alcohol with the product thus obtainediand, then cause ing formaldehyde to actJat temperaturesof about: -400. C; upon, the condensation product thus... obtained, saidproducts showing. good; tanning properties even 'at-highpH values.

3. The process which comprises vsulfonatingv a. mixture of colophony. and anaph-thol at elevated.

temperatures, reacting a phenol alcohol with the product thusobtained and then causing form-.

aldehyde toact at temperatures of about 90400? C. upon the condensation productthusobtained.

4. The-processwhich'compr-ises sulfonatinga mixture ofcolophony and a naphthol-at elevated temperatures, reacting-a phenol alcohol and a. phenol with the. product thus obtained "and then causing formaldehyde-- to act at temperatures of;

about 90400 0. upon the condensation product thus obtained.

5..The process which comprises. sulionating' amixture of colophony and anaphthol at elevated temperatures, reacting the sulfonation. product with a. mixture of phenol alcohols 'ob-' tained. by. causing formaldehyde to. actupona.

mixture. of phenols in the presence of an alkaline condensing. agent, and then causingforme aldehyde to act at temperatures of about 90-100? 0., upon the condensation product thus obtained.

GERTRUD THOMSENQ Administratrix' of the=Estate of Christoph Niko- ZausJalcobus Thom-sen, Deceased.

No references cited. 

1. THE PRODUCTS OBTAINED BY SULFONATING A MIXTURE OF COLOPHONY AND A NAPTHTHOL AT ELEVATED TEMPERATURES, REACTING A PHENOL ALCOHOL WITH THE PRODUCT THUS OBTAINED AND THEN CAUSING FORMALDEHYDE TO ACT AT TEMPERATURE OF ABOUT 90-100* C. UPON THE CONDENSATION PRODUCT THUS OBTAINED SAID PRODUCTS SHOWING GOOD TANNING PROPERTIES EVEN AT HIGH PH VALUES. 